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Public Key Infrastructure (PKI) & TLS
SSL Certificate Decoder & CSR Inspector
Decode PEM-formatted X.509 SSL/TLS certificates and CSRs. Inspect Common Name, Issuer CA, Subject Alternative Names (SAN), and expiration status.
PEM Certificate Data
Certificate Metadata
ValidPrimary Domain
nextools.org
Issuer CA
Let's Encrypt
Expires In
84 Days
| Common Name (CN) | nextools.org |
|---|---|
| Subject Alternative Names (SAN) | nextools.org, *.nextools.org |
| Issuer Organization | Let's Encrypt (R3) |
| Valid From (Not Before) | 2026-08-15 00:00:00 UTC |
| Valid Until (Not After) | 2026-11-13 23:59:59 UTC |
| Signature Algorithm | SHA-256 with RSA Encryption |
| Public Key Type | RSA (2048 Bits) |
| Serial Number | 03:a7:e4:91:fc:8b:20:d1:99:4a |
Why You Should Inspect SSL Certificates & Expiry Dates
An expired or misconfigured SSL certificate immediately triggers a prominent "Your connection is not private" (NET::ERR_CERT_DATE_INVALID) warning in Google Chrome and Safari, causing an immediate 95%+ drop in organic traffic. By inspecting raw certificate files and CSRs before server deployment, sysadmins verify domain wildcards, SAN coverage, and authority chains.
Frequently Asked Questions
Historically, the Common Name (CN) designated the single primary domain secured by a certificate. Modern web browsers and TLS 1.3 standards ignore CN in favor of the Subject Alternative Names (SAN) extension, which allows a single certificate to secure multiple domain names (e.g.
example.com and api.example.com).
Major browser root programs (Apple, Google, Mozilla) enforce a maximum TLS certificate lifespan of 398 days (approximately 13 months). Automated authorities like Let's Encrypt issue certificates with a 90-day lifespan to promote regular key rotation.